1. Field of the Invention
This invention relates to an optical disc housing a disc-shaped recording medium, such as an optical disc or a magneto-optical disc. More particularly, it relates to a disc cartridge having a shutter member adapted for opening/closing an aperture provided in the main cartridge body unit in which is housed a disc-shaped recording medium.
2. Description of Related Art
Up to now, a disc cartridge, having housed therein a disc-shaped recording medium, such as an optical disc or a magneto-optical disc, used as a recording medium for a recording and/or reproducing apparatus, has been in widespread use. As this sort of the disc cartridge, such a one constructed as shown in FIG. 1 has been in use. The disc cartridge 1, shown in FIG. 1, has rotatably housed therein an optical disc 5 in a disc housing unit provided in a main cartridge body unit 4 obtained on abutting and interconnecting upper and lower cartridge halves. In the upper and lower sides of the main cartridge body unit 4, housing the optical disc 5 therein, there is formed a recording and/or reproducing aperture 6 for exposing at least a portion of the signal recording surface of the optical disc housed in the disc housing unit to outside across the inner and outer rims of the disc and for allowing the recording and/or reproducing means, such as an objective lens or a magnetic head of the optical pickup device, to face the optical disc 5.
The disc cartridge 1 is loaded on the disc recording and/or reproducing apparatus, and is stored, as the optical disc 5 is housed therein. The disc cartridge 1 is fitted with a shutter member 7 for closing the aperture 6 during storage of the disc cartridge a and for opening the aperture 6 when loading the disc cartridge on the disc recording and/or reproducing apparatus, in order to prevent intrusion of dust and dirt or the like foreign matter through the aperture 6 during the storage of the disc cartridge and resulting contamination of the optical disc 5.
The shutter member 7 is formed from a thin metal sheet and fabricated by punching, bending and severing a metal sheet material. The shutter member 7 is made up of first and second shutter portions 7a, 7b, extending parallel to each other for closing the apertures 6 formed in the upper and lower sides of the main cartridge body unit 4, and a connecting piece 7c interconnecting the proximal ends of the shutter portions 7a, 7b, to an overall U-shaped profile. On one side of the connecting piece 7c is formed a movement guide portion 7d engaged with the front side of the lower cartridge half 3 and which is adapted for guiding the direction of movement of the shutter member 7. In the connecting piece 7c is bored an engagement opening 8 engaged by a movement controlling member provided on the recording and/or reproducing apparatus.
The shutter member 7, constructed as described above, is fitted from the front side of the main cartridge body unit 4, so that the first and second shutter portions 7a, 7b will extend over the aperture 6. At this time, the movement guide portion 7d is fitted on the front side of the lower cartridge half 3 and engagement pieces on the proximal side of the second shutter portion 7b and on the movement guide portion 7d are engaged in a movement guide groove formed in the outer surface of the lower cartridge half 3, whereby the shutter member 7 is prevented from being incidentally detached from the main cartridge body unit 4 and is mounted for movement along the front side of the main cartridge body unit 4.
On one corner of the front surface of the main cartridge body unit 4, there is arranged a shutter lock member 9 for controlling the movement of the shutter member 7 moved to the position of closing the aperture 6 provided in the main cartridge body unit 4 to maintain the closed state of the aperture 6. This shutter lock member 9, formed of synthetic resin, has a mounting portion 9a for the lower cartridge half 3 on its proximal end. From the mounting portion 9a, there is extended a resiliently flexible lock arm section 9b having a substantially U-shaped cross-section. The distal end of the lock arm section 9b is provided with an engagement recess 9c engaged by a lock piece 7e formed by bending a portion of the movement guide portion 7d of the shutter member 7. When the shutter member 7 is moved to a position of closing the aperture 6 provided in the main cartridge body unit 4, the lock piece 7e is engaged in the engagement recess 9c, so that the shutter lock member 9 controls the movement of the shutter member 7 to hold the aperture 6 in the closed state.
In the front surface of the main cartridge body unit 4 is formed an opening actuating member engagement groove 10 into which is intruded a shutter opening actuating member provided on the disc recording and/or reproducing apparatus for resiliently displacing the shutter lock member 9 to disengage the lock piece 7e from the engagement recess 9c. This engagement groove 10 is formed in the front surface of the main cartridge body unit 4 by into the lateral side perpendicular to the front surface of the main cartridge body unit 4.
When the above-described disc cartridge 1 is progressively introduced into the disc recording and/or reproducing apparatus, with one of the lateral sides perpendicular to the front side carrying the shutter member 7 as the inserting end, with the direction indicated by arrow X in FIG. 1 as an inserting direction, the movement controlling member 11 for the shutter member 7, provided on the disc recording and/or reproducing apparatus, rides on the movement guide portion 7d of the shutter member 7 and subsequently on the connecting piece 7c from the front side of the main cartridge body unit 4. Subsequently to riding of the movement controlling member 11 on the front surface of the main cartridge body unit 4, a shutter opening actuating member 12 provided on the disc recording and/or reproducing apparatus is intruded into the opening actuating member engagement groove 10 to cause resilient flexure of a lock arm section 9b of the shutter lock member 9 towards the inside of the main cartridge body unit 4. When the disc cartridge is further introduced into the disc recording and/or reproducing apparatus, the movement controlling member 11 is engaged in an engagement opening bored in the connecting piece 7c to control the movement of the shutter member 7. The shutter opening actuating member 12 also causes the lock arm section 9b towards the inside of the main cartridge body unit 4 to disengage the lock piece 7e from the lock recess 9c. 
When the shutter member 7 is unlocked to control the movement of the shutter member 7 and the disc cartridge 1 is subsequently introduced further into the interior of the recording and/or reproducing apparatus, the main cartridge body unit 4 is moved relative to the movement-controlled shutter member 7, in the direction indicated by arrow X in FIG. 1, to open the aperture 6. Since the shutter member 7 is maintained in its movement-controlled state by the movement controlling member 11, the shutter member 7 is maintained in its state of having opened the aperture 6. The optical pickup device and/or the magnetic head is allowed to face the optical disc 5 through this aperture 6 to permit recording and/or reproduction of information signals.
When the recording or reproduction of information signals recorded on or reproduced from the optical disc 5 comes to a close, and the disc is to be ejected, the disc cartridge 1 is moved to outside of the disc recording and/or reproducing apparatus in a direction opposite to the arrow X direction in FIG. 1. Since the shutter member 7 is maintained by the movement controlling member 11 in the movement-controlled state, only the main cartridge body unit 4 is moved relative to the shutter member 7 in a direction opposite to the arrow X direction in FIG. 1 to cause the shutter member 7 to perform relative movement in a direction of closing the aperture 6. When the shutter member 7 is moved to the position of closing the aperture 6, the lock piece 7e is engaged in the engagement recess 9c of the shutter lock member 9 to maintain the aperture 6 closed by the shutter member 7. At this time, the disc cartridge 1 is projected partially to outside of the disc recording and/or reproducing apparatus, so that, by gripping and pulling out the protruded portion of the disc cartridge 1 from the disc recording and/or reproducing apparatus, the disc cartridge 1 is taken out from the disc recording and/or reproducing apparatus.
In the above-described disc cartridge in which the movement of the shutter member is controlled in opening/closing the aperture provided in the main cartridge body unit, the movement controlling member is engaged with or disengaged from the engagement opening provided in the shutter member for effecting loading/unloading of the disc cartridge with respect to the recording and/or reproducing apparatus. In particular, the biasing force of thrusting the shutter member against the front side of the main cartridge body unit is applied to the movement controlling member to reliably control the shutter member movement. If the movement controlling member afforded with the biasing force is repeatedly engaged with and disengaged from the engagement opening, the inner peripheral surface of the engagement opening is worn out and roughed to render it impossible to effect smooth engagement/disengagement of the movement controlling member.
On the other hand, the movement controlling member is also damaged by repeated sliding contact with the inner peripheral surface of the engagement opening, so that the inner peripheral surface of the engagement opening is roughed to render it impossible to effect smooth engagement/disengagement of the movement controlling member when loading/unloading another disc cartridge the inner surface of the engagement opening of which is not roughed. Should the engagement opening and/or the movement controlling member be damaged, the frictional resistance when the movement controlling member is engaged with or disengaged from the engagement opening is increased. Consequently, a larger force is required when taking out the disc cartridge from the disc recording and/or reproducing apparatus so that the ejecting operation cannot be achieved with an optimum operating feeling.
Should the wear to the engagement opening and/or in the movement controlling member be excessive, the frictional resistance produced at the time of engaging/disengaging the movement controlling member is also increased, such that, the movement controlling member occasionally cannot be disengaged from the engagement opening, with the result that the ejection operation cannot be performed with an optimum operating feeling.
It is therefore an object of the present invention to provide a disc cartridge which can be reliably loaded/unloaded on or from the disc recording and/or reproducing apparatus to effect reliable opening/closure of the aperture provided in the main cartridge body unit.
It is another object of the present invention to provide a disc cartridge which is able to assure stable engagement/disengagement of the movement controlling member with respect to the shutter member over a prolonged period of time.
For overcoming the problems inherent in the above-described conventional disc cartridge and for achieving the above objects, the present invention provides a disc cartridge comprised of a main cartridge body unit and a disc as an information recording medium accommodated in the main cartridge body unit. In preparing an engagement opening engaged by a movement controlling member of the disc recording and/or reproducing apparatus and which is provided on a shutter member adapted for opening/closing an aperture provided in the main cartridge body unit housing the disc, the shutter member is punched so that the punched portion will be on an inner recessed side of the engagement opening. The punched portion is bent inwardly of the shutter member to provide a curved surface on which abuts the movement member to assure stable engagement/disengagement in the engagement opening of the movement controlling member to prevent the inner peripheral surface of the engagement opening and the peripheral surface of the movement controlling member from being damaged by repeated engagement/disengagement of the movement controlling member.